WASHINGTON, July 8 (UPI) -- Senators came away from a classified briefing Tuesday on the Pentagon's plans to deal with the takeover of Iraq by terrorists without many answers on the way forward.

In the first of three related hearings planned for this week, Defense Secretary Chuck Hagel and Joint Chiefs of Staff Chairman Gen. Martin Dempsey appraised the Senate Armed Forces Committee of their efforts to stave off the advancing Islamic State of Iraq and Syria (ISIS).

So far, the president has sent 800 U.S. troops to Iraq to advise the Iraqi government and protect U.S. facilities in the war-torn nation.

Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., have been among the administration's loudest critics, calling for airstrikes against ISIS. Exiting the hearing Tuesday, McCain said he heard little to like from Hagel and Dempsey.

"There is no strategy for countering the largest enclave of terrorism in history on the Iraq-Syria border," he said. "They have no strategy, nor could they articulate a strategy to counter what our intelligence estimates say will be a direct threat to the United States."

"No one gave us a scenario where the safe havens ISIS enjoys in Syria and Iraq could be eradicated without some American military force," Graham added. "Name a force that could dislodge these people and deny them their safe haven in the region that doesn't include American airpower."

Meanwhile, senior Democrats on the committee said they felt the administration's strategy of extreme caution was the appropriate approach.

"What needs to happen right now is they need to complete that assessment of the capability of the Iraqi army, and as to how we can be helpful," said committee Chairman Carl Levin, D-Mich. "More importantly is to see whether the Iraqis are up to coming together against a common enemy. ISIS is the common enemy."

Sen. Claire McCaskill, D-Mo., said the involvement of Iran, with whom the U.S. unusually finds itself aligned with Iraq Shiite Prime Minister Nouri al-Maliki against the Sunni-backed ISIS, requires the U.S. to be more circumspect than usual.

"We've got Iran very active in Iraq, trying to help the Maliki government, at the same time they're very active in Syria trying to help [Syria Prime Minister Bashar al-Assad]," she explained, while acknowledging Maliki's failure to form an inclusive government of both Shiites and Sunnis that has given ISIS an opening.

McCaskill disagreed with her Republican colleagues, coming away from the briefing with a sense that the Pentagon had a strategy going forward, but it might not be the "simple soundbite" they were hoping for.

"If the American people were looking for some simple soundbite, it would be irresponsible to give one because it's complicated," she said. "I think the administration is being appropriately cautious and careful that there is not one side to this all in the Middle East right now."

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